Corrosion inhibitors for gasolines



United States Patent Ofi ice 3,294,501 Patented Dec. 27, 1966 3,294,501CORROSION INHIBITORS FOR GASOLINES Fred'K. Kawahara, Park Forest, 111.,assignor to Standard Oil Company, Chicago, 11]., a corporation ofIndiana No Drawing. Filed Nov. 13, 1964, Ser. No. 411,146

1 Claim. (Cl. 44-71) V This is a continuation-in-part of US. patentapplication Ser. No. 234,557, now abandoned.

This invention relates to corrosion inhibitors for gasolines. Moreparticularly it relates to the use of certain corrosion inhibitors forgasolines which contain tetraaIkyl-lead and a benzoic-acid or ahexahydrobenZoic-acid type lead appreciator.

For the most part, motor gasolines that are marketed in this countrycontain tetra-alkyl lead compounds such as tetramethyl or tetraethyllead to upgrade their octane ratings. Recently, it has been found thatcertain organic compounds possess the unusual feature of enhancing theeffectiveness of tetra-alkyl lead compounds. Two such compounds arebenzoic acid and hexahydrobenzoic acid (i.e., cyclohexane carboxylicacid). This phenomenon of enhancing the effectiveness of tetra-alkyllead compounds is termed lead appreciation and is currently receivingscientific as well as commercial attention.

Both benzoic acid and hexahydrobenzoic acid are very corrosive withrespect to several metals, particularly when in contact with moisture.Gasolines containing either of these compounds are particularlycorrosive toward zinc or zinc alloys. Both zinc and zinc alloys are usedextensively in fuel pumps, carburetors and other diecast parts ofautomative and aviation engines.

It has now been discovered pursuant to the invention that thecorrosiveness toward zinc and zinc alloys of gasolines containing eitherbenzoic acid or hexahydro- 'benzoic acid as a lead appreciator may besubstantially inhibited by incorporating into the gasoline a smallamount of one or more of the following additives:

Picric acid 3;5 dintrosalicyclic acid S-nitrosalicyclic acid1-hydroxy-2-naphthoic acid 3-hydroxy-2-naphthoic acid 2,4,5-trihydroxy=butyrophenone 5 ,5 '-methylene disalicyclic acid 2,4-'dinitrophenol Ithas been found that the effectiveness of the foregoing inhibitors may beconsiderably enhanced, in certain cases, by utilizing a combination ofinhibitors, as will be shown presently. I

An additional discovery associated with the present invention is thatthe effectiveness of the foregoing inhibitors may be enhanced evenfurther by adding to the inhibited gasoline a small amount of trihydroxydecanophenone, which is, by itself an ineffective corrosion inhibitor.It has been demonstrated also that many compounds which may be suggestedby the prior art as inhibiting ferrousmetal corrosion and which areclose analogs of the inventive additives fail to exhibit any substantialdegree.

of inhibition of corrsion of zinc in the presence of benzoic by theresults from tests made with such compounds as 2,4-dihydroxy benzoicacid, p-hydroxy benzoic acid, salicyclic acid, beta-naphthoic acid,Z-hydroxy stearic acid, dl-mandelic acid and citrimic acid.

The various tests employed in this series of experiments, as well asthose reported later, involved the following procedure. For each test,100 ml. of leaded gasoline were poured into a tall-form bottle. In someof these tests, the leaded gasoline contained no other substances. Inothers, the leaded gasoline contained 02% hexahydrobenzoic acid; andstill in others, the leaded gasoline contained both hexahydrobenzoicacid and an anti-corrosion agent.

A weighted strip of metal was then immersed in each gasoline sample.After a; particular strip had been immersed for 30 minutes, 10 ml. ofwater were added and the bottle was rolled for one minute. After threedays of immersion, each metal strip was removed, scrubbed,

' and washed to removed corrosion products and reweighed. The loss inweight was taken as a measure of effectiveness of the particularcorrosion inhibitor. The results of this series of tests, which usedstrips of zinc metal and anti-corrosion agents suggested by the priorart, are reported in Table I below:

TABLE I Zinc Test Gasoline Composition Ifiss,

Leaded 2a saline As in- Test 1 plus 0.2% cyclohexane carboxylic acid- Asin Test 2plus 2,4-dihydroxybenzoic acid (30 PIB As in Test 2 plusp-hydroxybenzoic acid (30 PTB As in Test 2 plus alicyclic acid (30 PTBLeaded a saline As in Test 6 plus 0.2% cyclohexane carboxylic acid As inTest 7 plus 2-hydroxy stearieacid (30 PTB As in Test 7 plus dl-mandelieacid (30 PTB Leaded gasoline As in Test 10 plus 0.2% cyclohexanecarboxylic acid.

As in Test 11 plus citrimic acid (30 PTB 1 Concentration of additive inpounds per thousand barrels of gasoline.

The results of Tests 2, 7 and 11 demonstrate that hexahydrobenzoic acid,i.e., cyclohexane carboxylic acid, is very corrosive toward zinc. Theresults of Tests 3, 4 and 5 indicate that 2,4-dihydroxybenzoic acid,p-hydroxybenzoic acid and salicyclic acid, individually, did notappreciably reduce the corrosive action of the cyclohexane carboxylicacid on the zinc. Furthermore, the results of Tests 8, 9 and 12indicatethat 2-hydroxy stearic acid, dl-mandelic acid and citrimic acid,individually, did not reduce the corrosiveness of the cyclohexanecarboxylic acid toward zinc.

These results establish that anti-corrosion inhibitors of the six typessuggested by the prior art do not inhibit the corrosion of zincresulting from the presence of cyclohexane carboxylic acid(hexahydrobenzoic acid).

The quantities of the inventive additives that are incorporated intogasolines for internal combustion engines are not crucial. Thesequantities depend upon the amount of the benzoic acid orhexahydrobenzoic acid (cyclohexane carboxylic acid) that is present, theservice conditions of storage and use, the nature of the inhibitor, andother similar factors. It has been found that excellent corrosioninhibitionis obtained at additive concentrations of as little as 30pounds of additive per thousand barrels of gasoline (42 gallons perbarrel), although this TABLE II amount may be increased or decreased asa matter of pref- Zinc Loss, Mg" ercnce. Quantities as little as 0.5pound per thousand H Alterbarrels of gasoline, or even less, areeffective, while quan- 5 Test Gasolme Composltlon tities of as much as100 pounds per thousand barrels, or 3 Days 5 Days more, may be used in aparticularly serious situation.

The other constituents of the gasoline will depend upon Leaded gasolinethe manufacturers specifications and the consumers refix: f1???tiifilgfifg fifijifigigii lfi 19572213 32's quirements. Ordinarily, thegasoline is predominantly a tyrophenone 0 PTB hydrocarbon, havingparaffin, naphthene, olefin and aroti tit t It tai a t tra a1ky1 l ad at3 Concentration of additiveinpounds per thousand barrels of gasoline.concentration ordinarily within the range of 0.5 to about Th lt f T t 14how th corrosive action of the 6 Cubic centimeters P gallon, dePehdihg1111011 market benzoic acid toward zinc. The results from Testrequirements It also y contain either behzoic acid 15 show theinhibition of such corrosion by the use of 2,4,5- or hexahydrobenzoicacid, advantageously in the freetrihydroxy butyrophenone, acid form,although derivatives such as the methyl In the second series of tests,hexahydrobenzoic acid other gasoline-soluble esters may be used. Theamount (cyclohexane b li id was used as h lead of the benzoic acid orhexahydrobenzoic acid mayrange predator, A number of organic compoundswas used from as iittie as 0-005 Weight Percent to about Weight toinhibit the corrosive effect of the lead appreciator on Percent As Wasnoted above, this q y is not Critical zinc. In addition, variouscombinations of these inhibiahd y be greater of smaller than theforegoing range tors were employed. In general, the concentration of anfor as much as all Order Of magnitude, if this is quired. inhibitor,when used alone, was 30 pounds of the inhibitor The inventive additiveswere evaluated in a number of r 1000 barrel of the gasoline, In the caseof the use tests employing the simple laboratory tests discussed ofmultiple inhibitors, the total quantity of the inhibitors above. In someof these tests, the corrosive action of did not exceed pounds per 1000barrels. Equal porhEXahYdIOhBHZOiC acid, as inhibited y selected tionsof the inhibitors were employed; for example, in pounds, was determinedwith iron and copper strips, as Test 29 corrosive inhibition of the zincwas brought about well as zinc strips. In each case the metal stripswere of by the use of 15 pounds of 3-hydroxy-2-naphthoic acid uniformsize, about 2 /2 inches long by /2 inch wide. 30 per 1000 barrels ofgasoline and 15 pounds of 2,3,4-tri- Each zinc strip weighedapproximately 1.5 gr.; each hydroxy decanophenone per 1000 barrels ofgasoline, iron strip weighed about 2.4 gr.; and each copper strip, whilein Test 36 corrosion inhibition resulted from the about 3.7 gr. use of10 pounds of picric acid per 1000 barrels of gaso- In the first seriesof tests, benzoic acid was used as the line, 10 pounds ofS-nitrosalicylic acid per 1000 barrels lead appreciator and zinc stripswere employed. The re- 35 of gasoline and 10 pounds of3,5-dinitrosalicylic acid per sultts from the tests of this series arepresented in 1000 barrels of gasoline. The results of the tests madeTable II. in this series are presented in Tables III and 1V.

TABLE III Concen Zine Loss Aiter Specified N 0. 01 Days, Mg. TestGasoline Composition tration,

PTBI

Leaded gasoline 0.5 0 3-1 4 0. 5-2.9 2.3 0.0 0.3 0.2 Leaded gasoline and0.2% hexahydrobenzoic acid 29. 6-34. 1 30. 8 31. 1-31. 8 34. 2 42. 342.1

As in Test 17 plus picric acid As in Test 17 plus 3,5-dinitrosalicylicacid.

As in Test 17 plus 5-nitrosalicylic acid As in Test 17 plusl-hydroxy-Z-naphthoic aci As i3 Test 17 plus 3-hydroxy-2-naphthoie acidAs in Test 17 plus 5,5-n1ethylene disalicylic aci 30 7. 1 As in Test 17plus 4-cthoxy-2-hydroxybenzoic aci 3O 9. 2 As in Test 17 plus2,4-dinitrophenol 30 5.1 As in Test 17 plus 3,5-dinitrosalicylic acidand 15 3-hydr0xy-2-naphthoic acid. 15 2. 2 2. 3

1 Concentration of additives in pounds per thousand barrels of gasoline.

TABLE IV Zinc Loss After Specified No. Concen- Days, Mg. Test GasolineComposition tlnaltion, 1

28 As in Test 17 plus 2,3,4-trihydroxy decanoplienone 30 23. 0 29 As inTest 17 plus 3-hydroXy-2naphthoic acid and 15 O 7 5 2 3 3 4 72,3,4-trihydroxy decanophenone. 15 30 As in Test 17 plus3-liydroxy-2-naphthoic acid and 7. 5 1 1 19 0 2,3,4-trihydroxydecanophenone. 7. 5 31 As in Test 17 plus picric acid and 15 1 9 21 4 36 32 1 3-hydroxy-2-naphthoic acid. 15 32 As in Test 17 plus picrie acidand 7. 5 24 2 33 7 3-hydroxy-2-naphthoic acid. 7. 5 33 As in Test 17plus 3,5-dinitr0salicylic acid and 15 2 2 2 3 3-hydroxy-2-naphthoicacid. 15 34 As in Test 17 plus 3,4-dinitr0sa1icylie acid and 7. 5 4 8 127 3-hydroxy-2-naphth0ic acid. 7. 5 35 As in Test 17 plus picric acid and15 4 6 4 0 5-nitrosalicy in acid. 15 36 As in Test 17 plus pieric acidand 10 5-nitrosalicylic acid and 10 7 4 3,5-dinitrosalicylie acid. 10 37As in Test 17 plus picrie acid and 10 3-hydroxy-2-naphthoie acid and 109 8 2,3,4-trihydroxy dccanophcnone. l0

1 Concentration of additive in pounds per thousand barrels of gasoline.

The corrosive nature of hexahydrobenzoic acid toward zinc is clearlyshown by Test 17'. Examination of the reto inhibit the corrosive effectof hexahydrouenzoic acid on zinc. The results of these tests are shownin Table VI.

TABLE VI Zinc Loss, Mg. Immer- Test Gasoline Composition si0n,-

' Days Fresh Sea Water Water 48 Leaded gasoline 33 0. 4 2. 2 49 Leadedgasoline and 0.2% hexahydrobenzoic acid.-. 33 28. 4 32. 0 50 As in Test49 plus picric acid and 3-hydroxy-2-naph- 33 0.3 1. 0

thoic acid and 2,3,4trihydroxy decanophenone. 51 Leaded gasoline 70 0. 315. 3 52 Leaded gasoline and 0.2% hexahydrobenzoic acid 70 43. 3 40. 253 As in Test 52 plus picric acid and 3-hydroxy-2-naph- 70 1. 8

them acid and 2,3,4-trihydroxy decanophenone.

sults from Tests 18-28 show the eifectiveness of the various compoundsin inhibiting the corrosion of Zinc due to the presence ofhexahydrobenzoic acid. Only the compound used in Test 28,2,3,4-trihydroxy decanophenone, does not greatly reduce the corrosion.However, the use of 2,3,4-trihydroxy decanophenone in conjunction withanother additive improves the corrosion inhibition due to the use of theother additive. Compare the results from Test 22 with those from Test29. Furthermore, combinations of the various compounds seem to inhibitthe corrosive efi'ect toward zinc, at least When the combinations areused in a concentration of 30 pounds of insibitors per 1000 barrels ofgasoline. For example, in Test 31, the combination of picric acid and3-hydroxy- Z-naphthoic acid in a combined concentration of 30 pounds per1000 barrels of gasoline inhibits the corrosive action at least after 14days of immersion. However, when the total concentration was halved, asshown in Test 32, substantial corrosion had occurred after the sameperiod of time.

The results of the tests made with the iron and copper strips arepresented in Table V.

These results indicate that although the sea water has a very corrosiveeffect on inc, even without the presence of the lead appreciator, theabove combination of corrosion inhibitors minimized the corrosive effecton zinc when the zinc had been immersed in the solution for 70 days.

Thus it is evident that there has been provided, :according to theinvention, an outstanding procedure for inhibiting the corrosiveness ofgasolines which contain one or more of the following lead appreciators:benzoic acid and hexahydrobenzoic acid. While the invention has beendescribed in conjunction with specific embodiments thereof, these arepresented for illustration only. Accordingly, many alternatives,modifications and variations will be apparent to those skilled in theart. In view of the foregoing description, it is full intended toembrace all such alternatives, modifications and variations as fullywithin the spirit of broad scope of the appended claim.

What is claimed is:

A gasoline containing, as a lead appreciator, a member selected from thegroup consisting of benzoic acid and hexahydrobenzoic acid together witha first additive TABLE V Metal Loss After Specified No. of Days, Mg.Concen- Test; Gasoline Composition tration,

PTB 1 Iron Copper Leaded nasnline 0. 8 3. 7 0. 3 0. 5 Leaded gasolineand 0.2% hexahydrobenzoic acid 6. 6 6. 9 7. l 9. 4 As in Test 39 pluspieric acid 30 1. 3 As in Test 39 plus 2,3,4-trihydroxy decanophen 300.9 As in Test 39 plus 3-hydroxy-2-naphthoic acid and 15 3' 1 1 8 2. 7

2,3,4-trihydroxy decanophenone. l5 As in Test 39 plus3-hydroxy-2naphthoic acid and 7. 5 4 1 6 3 2,3,4-trihydroxydecanophenone. 7. 5 As in Test 39 plus picric acid and l5 5 9 L 1 A3- hy(Ii ro b2-n1apthoic acid(.1 d 1; 5

s in es p us plcric aci an A3-hy grog2-riaphthgic agaidl 1 d d i 7.5 1 2O 4 1 8 1 1 s in es p us 3,5- ini rosa icy ic aci an 15 A %'i%5 "i ?i t1 1 d d 5 L3 0.6 L1 1.2

s in es p us 3,5- ini rosa icy ic aci an 3-hydroxy-2-naphtoic acid. 7.51 5 1 Concentration of additive in poinids per thousand barrels ofgasoline.

These results demonstrate that the use of the inventive and a secondadditive said first additive being em 10 ed e o l a l u u 1 I o p ycompounds will not detenously affect these metals. in COIIJHI'lCtlOllwlth said second additlve, said first add1- Hence, they can be usedsafely to inhibit the corrosive tive comprising at lea-st one member ofthe group consistnature of the benzoic acid or hex-ahydrobenzoie acidtomg ward zinc without seriously affecting the iron and copper Picricacid in the system. 3,5-dinitrosalicylic acid In another series oftests, sea water, as well as fresh S-nitrosalicylic id water was used.The sea water was a synthetic prepal-hydroxy-Z-na hthoic acid 5 I p aration made according to the specification of ASTM3-hydroxy-2-na-phtho1c acid Preparation D-665. The zinc strips wereimmersed in 2, ,5-tr1hydr0Xy butyrophenone the various solutions fore1ther 33 or days. A comb1 5,5 m y dlsallcyhc acld nation of picricacid, 3-hydroxy-2-naphthoic acid, and 2, 7 A- P 3,4-trihydroxydecanophenone, each in a concentration of 10 pounds per 1000 barrels ofgasoline, was employed said second additive being 2,3,4-trihydroxydecanophenone, the amount of said first additive being eifective toprovide inhibition of the corrosiveness of gasoline containing Waterwith respect to zinc, and the amount of said second additive beingeffective to improve said inhibition which results from the use of saidfirst additive.

References Cited by the Examiner UNITED STATES PATENTS 2,334,158 11/1943Von Fuchs et a1 4470 2,349,044 5/1944 Jahn 10614 DANIEL E. WYMAN,Primary Examiner. Y. H. SMITH, Assistant Examiner.

